Methods and systems for controlling braking of a vehicle when the vehicle is stationary

ABSTRACT

A method for controlling braking of a vehicle includes the steps of calculating a first pressure based on a driver request, and providing pressure that does not exceed a predetermined pressure threshold if the vehicle is stationary and the first pressure is less than the predetermined pressure threshold.

TECHNICAL FIELD

The present invention generally relates to the field of vehicles and,more specifically, to methods and systems for controlling braking ofvehicles.

BACKGROUND OF THE INVENTION

Automobiles and various other vehicles include braking systems forreducing vehicle speed or bringing the vehicle to a stop. Such brakingsystems generally include a controller that provides braking pressure tobraking calipers of the braking system to produce braking torque for thevehicle. For example, in a hydraulic braking system, hydraulic brakingpressure is provided to the braking calipers to produce braking torquefor the vehicle. However, excessive braking pressure, such as excessivehydraulic braking pressure, can cause increases in braking drag andenergy consumption, pedal feedback, and/or increased hydraulic fluidconsumption and pump cycling.

Accordingly, it is desirable to provide an improved method forcontrolling braking for a vehicle that limits braking pressure of thevehicle when appropriate. It is also desirable to provide an improvedsystem for such controlling of braking for a vehicle that limits brakingpressure of the vehicle when appropriate. Furthermore, other desirablefeatures and characteristics of the present invention will be apparentfrom the subsequent detailed description and the appended claims, takenin conjunction with the accompanying drawings and the foregoingtechnical field and background.

SUMMARY OF THE INVENTION

In accordance with an exemplary embodiment of the present invention, amethod for controlling braking of a vehicle is provided. The methodcomprises the steps of calculating a first pressure based on a driverrequest, and providing pressure that does not exceed a predeterminedpressure threshold if the vehicle is stationary and the first pressureis less than the predetermined pressure threshold.

In accordance with another exemplary embodiment of the presentinvention, a method for controlling braking of a vehicle during abraking event is provided. The method comprises the steps of calculatinga plurality of pressures during the braking event, each of the pluralityof pressures calculated based on a different one of a plurality ofdriver requests, and providing pressure that does not exceed apredetermined pressure threshold if the vehicle is stationary and any ofthe plurality of pressures are less than the predetermined pressurethreshold.

In accordance with a further exemplary embodiment of the presentinvention, a system for controlling braking of a vehicle during abraking event is provided. The system comprises a sensor and aprocessor. The sensor is configured to detect a plurality of driverrequests during the braking event. The processor is coupled to thesensor. The processor is configured to at least facilitate calculating aplurality of pressures during the braking event, each of the pluralityof pressures calculated based on a different one of the plurality ofdriver requests, and providing pressure that does not exceed apredetermined pressure threshold if the vehicle is stationary and any ofthe plurality of pressures are less than the predetermined pressurethreshold.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction withthe following drawing figures, wherein like numerals denote likeelements, and wherein:

FIG. 1 is a functional block diagram of a braking system for a vehicle,such as an automobile, in accordance with an exemplary embodiment of thepresent invention;

FIG. 2 is a flowchart of a process for controlling braking in a vehicle,such as an automobile, and that can be utilized in connection with thebrake controller of FIG. 1, in accordance with an exemplary embodimentof the present invention; and

FIG. 3 is a depiction of exemplary graphical representation of varioustorque parameters pertaining to the brake controller of FIG. 1 and theprocess of FIG. 2 for an exemplary scenario in which the vehicle isbeing operated, in accordance with an exemplary embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description of the invention is merely exemplaryin nature and is not intended to limit the invention or the applicationand uses of the invention. Furthermore, there is no intention to bebound by any theory presented in the preceding background of theinvention or the following detailed description of the invention.

FIG. 1 is a block diagram of an exemplary braking system 100 for use ina brake-by-wire system of vehicle, such as an automobile. In a preferredembodiment, the vehicle comprises an automobile, such as a sedan, asport utility vehicle, a van, or a truck. However, the type of vehiclemay vary in different embodiments of the present invention.

As depicted in FIG. 1, the braking system 100 includes a brake pedal102, a brake controller 104, and a plurality of brake units 106. Thebraking system 100 is used in connection with one or more wheels 108 ofthe vehicle. In a preferred embodiment, certain of the brake units 106are disposed along a first axle 130 of the vehicle along with certain ofthe wheels 108, and certain other of the brake units 106 are disposedalong a second axle 132 of the vehicle along with certain other of thewheels 108. In one exemplary embodiment, the first axle 130 is aregenerative braking axle, and the second axle 132 is a non-regenerativebraking axle 132. However, this may vary in other embodiments.

The brake pedal 102 provides an interface between an operator of avehicle and a braking system or a portion thereof, such as the brakingsystem 100, which is used to slow or stop the vehicle. To initiate thebraking system 100, an operator would typically use his or her foot toapply a force to the brake pedal 102 to move the brake pedal 102 in agenerally downward direction. In one preferred embodiment the brakingsystem 100 is an electro-hydraulic system. In another preferredembodiment, the braking system 100 is a hydraulic system.

The brake controller 104 is coupled between the brake pedal 102, thebrake units 106, and the first and second axles 130, 132. Specifically,the brake controller 104 monitors the driver's engagement of the brakepedal 102 and controls braking of the vehicle to limit or conservebraking pressure of the braking system 100 via braking commands sent tothe brake units 106 by the brake controller 104 along the first andsecond axles 130, 132 when appropriate.

In the depicted embodiment, the brake controller 104 comprises one ormore brake pedal sensors 110, one or more wheel speed sensors 111, and acomputer system 112. In certain embodiments, the brake controller 104may be separate from the brake pedal sensors 110 and/or the wheel speedsensors 111, among other possible variations. In addition, it will beappreciated that the brake controller 104 may otherwise differ from theembodiment depicted in FIG. 1, for example in that the brake controller104 may be coupled to or may otherwise utilize one or more remotecomputer systems and/or other control systems.

The brake pedal sensors 110 are coupled between the brake pedal 102 andthe computer system 112. Specifically, in accordance with variouspreferred embodiments, the brake pedal sensors 110 preferably includeone or more brake pedal force sensors and/or one or more brake pedaltravel sensors. The number of brake pedal sensors 110 may vary. Forexample, in certain embodiments, the brake controller 104 may include asingle brake pedal sensor 110. In various other embodiments, the brakecontroller 104 may include any number of brake pedal sensors 110.

The brake pedal travel sensors, if any, of the brake pedal sensors 110provide an indication of how far the brake pedal 102 has traveled, whichis also known as brake pedal travel, when the operator applies force tothe brake pedal 102. In one exemplary embodiment, brake pedal travel canbe determined by how far an input rod in a brake master cylinder hasmoved.

The brake pedal force sensors, if any, of the brake pedal sensors 110determine how much force the operator of braking system 100 is applyingto the brake pedal 102, which is also known as brake pedal force. In oneexemplary embodiment, such a brake pedal force sensor, if any, mayinclude a hydraulic pressure emulator and/or a pressure transducer, andthe brake pedal force can be determined by measuring hydraulic pressurein a master cylinder of the braking system 100.

Regardless of the particular types of brake pedal sensors 110, the brakepedal sensors 110 detect one or more values (such as brake pedal traveland/or brake pedal force) pertaining to the drivers' engagement of thebrake pedal 102. The brake pedal sensors 110 also provide signals orinformation pertaining to the detected values pertaining to the driver'sengagement of the brake pedal 102 to the computer system 112 forprocessing by the computer system 112.

The wheel speed sensors 111 are coupled between one or more of thewheels and the computer system 112. Specifically, the wheel speedsensors 111 detects information pertaining to movement of one or more ofthe wheels 108, and provide signals or information pertaining thereto tothe computer system 112.

In the depicted embodiment, the computer system 112 is coupled betweenthe brake pedal sensors 110, the wheel speed sensors 111, the brakeunits 106, and the first and second axles 130, 132. The computer system112 receives the signals or information pertaining to the drivers'engagement of the brake pedal 102 from the brake pedal sensors 110 andthe signals or information pertaining to the speed of one or more of thewheels 108. The computer system 112 further processes these signals orinformation in order to control braking of the vehicle and limit orconserve braking pressure of the braking system 100 via braking commandssent to the brake units 106 by the computer system 112 along the firstand second axles 130, 132 when appropriate, for example to reducebraking drag, energy consumption, pedal feedback, hydraulic fluidconsumption, and/or pump cycling. In a preferred embodiment, these andother steps are conducted in accordance with the process 200 depicted inFIG. 2 and described further below in connection therewith.

In the depicted embodiment, the computer system 112 includes a processor114, a memory 118, an interface 116, a storage device 124, and a bus126. The processor 114 performs the computation and control functions ofthe computer system 112 and the brake controller 104, and may compriseany type of processor or multiple processors, single integrated circuitssuch as a microprocessor, or any suitable number of integrated circuitdevices and/or circuit boards working in cooperation to accomplish thefunctions of a processing unit. During operation, the processor 114executes one or more programs 120 contained within the memory 118 and,as such, controls the general operation of the brake controller 104 andthe computer system 112.

The memory 118 can be any type of suitable memory. This would includethe various types of dynamic random access memory (DRAM) such as SDRAM,the various types of static RAM (SRAM), and the various types ofnon-volatile memory (PROM, EPROM, and flash). The bus 126 serves totransmit programs, data, status and other information or signals betweenthe various components of the computer system 112. In a preferredembodiment, the memory 118 stores the above-referenced program 120 alongwith one or more threshold values 122 that are used in controlling thebraking and limiting the braking pressure when appropriate in accordancewith the steps of the process 200 depicted in FIG. 2 and describedfurther below in connection therewith.

The interface 116 allows communication to the computer system 112, forexample from a system driver and/or another computer system, and can beimplemented using any suitable method and apparatus. It can include oneor more network interfaces to communicate with other systems orcomponents. The interface 116 may also include one or more networkinterfaces to communicate with technicians, and/or one or more storageinterfaces to connect to storage apparatuses, such as the storage device124.

The storage device 124 can be any suitable type of storage apparatus,including direct access storage devices such as hard disk drives, flashsystems, floppy disk drives and optical disk drives. In one exemplaryembodiment, the storage device 124 comprises a program product fromwhich memory 118 can receive a program 120 that executes one or moreembodiments of one or more processes of the present invention, such asthe process 200 of FIG. 2 or portions thereof. In another exemplaryembodiment, the program product may be directly stored in and/orotherwise accessed by the memory 118 and/or a disk such as thatreferenced below.

The bus 126 can be any suitable physical or logical means of connectingcomputer systems and components. This includes, but is not limited to,direct hard-wired connections, fiber optics, infrared and wireless bustechnologies. During operation, the program 120 is stored in the memory118 and executed by the processor 114.

It will be appreciated that while this exemplary embodiment is describedin the context of a fully functioning computer system, those skilled inthe art will recognize that the mechanisms of the present invention arecapable of being distributed as a program product in a variety of forms,and that the present invention applies equally regardless of theparticular type of computer-readable signal bearing media used to carryout the distribution. Examples of signal bearing media include:recordable media such as floppy disks, hard drives, memory cards andoptical disks, and transmission media such as digital and analogcommunication links. It will similarly be appreciated that the computersystem 112 may also otherwise differ from the embodiment depicted inFIG. 1, for example in that the computer system 112 may be coupled to ormay otherwise utilize one or more remote computer systems and/or othercontrol systems.

The brake units 106 are coupled between the brake controller 104 and thewheels 108. In the depicted embodiment, some of the brake units 106 aredisposed along the first axle 130 and are coupled to certain wheels 108on the first axles 130, and other of the brake units 106 are disposedalong the second axle 132 and are coupled to other wheels 108 on thesecond axle 132. The brake units 106 receive the braking commands fromthe brake controller 104, and are controlled thereby accordingly.

The brake units 106 can include any number of different types of devicesthat, upon receipt of braking commands, can apply the proper brakingtorque as received from the brake controller 104. For example, in anelectro-hydraulic system, the brake units 106 can comprise an actuatorthat can generate hydraulic pressure that can cause brake calipers to beapplied to a brake disk to induce friction to stop a vehicle.Alternatively, in an electro-mechanical brake-by-wire system, the brakeunits 106 can comprise a wheel torque-generating device that operates asa vehicle brake. The brake units 106 can also be regenerative brakingdevices, in which case the brake units 106, when applied, at leastfacilitate conversion of kinetic energy into electrical energy.

FIG. 2 is a flowchart of a process 200 for controlling braking in avehicle and for limiting braking pressure when appropriate, inaccordance with an exemplary embodiment of the present invention. Theprocess 200 can be implemented in connection with the braking system 100of FIG. 1, the brake controller 104 and/or the computer system 112 ofFIG. 1, and/or program products utilized therewith, in accordance withan exemplary embodiment of the present invention. The process 200 willalso be described below in connection with FIG. 3, which depicts agraphical representation 300 of various parameters pertaining to theprocess 200 in accordance with one exemplary embodiment of the presentinvention and with operation of the vehicle in one exemplary scenario.

As depicted in FIG. 2, the process 200 begins with the step of receivingone or more braking requests (step 202). The braking requests preferablypertain to values pertaining to engagement of the brake pedal 102 ofFIG. 1 by a driver of the vehicle. In certain preferred embodiment, thebraking requests pertain to values of brake pedal travel and/or brakepedal force as obtained by the brake pedal sensors 110 of FIG. 1 andprovided to the computer system 112 of FIG. 1. Also in a preferredembodiment, the braking requests are received and obtained, preferablycontinually, at different points or periods in time throughout a brakingevent for the vehicle.

In certain embodiments, a filter is applied to one or more of thebraking requests (step 204). In one preferred embodiment, a first orderfilter is applied to a corresponding braking request that will be usedin controlling braking for the vehicle, such as a most recent brakingrequest. However, this may vary in other embodiments. In a preferredembodiment, the filter, if applied, is applied by the processor 114 ofFIG. 1, to thereby generate a filtered braking request.

A requested amount of braking pressure is calculated (step 206). Therequested amount of braking pressure preferably corresponds to a certainamount of braking pressure that corresponds to the engagement of thebrake pedal 102 by the driver of the vehicle, and that is imputed to thedriver as a desired amount of braking pressure based upon the driver'sengagement of the brake pedal 102. The requested amount of brakingpressure is preferably calculated by the processor 114 of FIG. 1. In onepreferred embodiment, the requested amount of braking pressure iscalculated using a corresponding, and preferably most recent, brakingrequest directly from step 202. In another preferred embodiment, therequested amount of braking pressure is calculated using acorresponding, and preferably most recent, braking request from step 202indirectly as filtered during step 204, thereby using the filteredbraking request generated in step 204.

In addition, one or more wheel speed values are obtained for the vehicle(step 208). In one preferred embodiment, the wheel speed values areobtained by one or more of the wheel speed sensors 111 of FIG. 1 coupledto one or more of the wheels 108 of FIG. 1 and provided to the processor114 of FIG. 1 for processing. In another preferred embodiment, the wheelspeed values are calculated by the processor 114 of FIG. 1 based on rawdata, signals, or other information obtained by one or more of the wheelspeed sensors 111 of FIG. 1 and provided to the processor 114 of FIG. 1for processing.

A determination is made as to whether the vehicle is stationary (step210). In a preferred embodiment, this determination is made by theprocessor 114 of FIG. 1 using the wheel speed values obtained during theabove-described step 208. However, this may vary in other embodiments.For example, in certain other embodiments, this determination may bemade using one or more other techniques, such as the processing ofinformation from a global-positioning system (GPS) device used inconnection with the vehicle.

If it is determined in step 210 that the vehicle is stationary, then adetermination is made as to whether any of the requested amounts ofbraking pressure from step 206 thus far during the braking event havebeen less than a predetermined pressure threshold (step 212). In apreferred embodiment, the predetermined pressure threshold comprises avalue of braking pressure that generally would not need to be exceededwhile the vehicle is stationary on a smooth and flat surface undertypical driving conditions. In certain preferred embodiments, thepredetermined pressure threshold is within the range of 10-20 bar ofhydraulic pressure. Also in a preferred embodiment, the predeterminedpressure threshold is stored in the memory 118 of FIG, 1 as one of thethreshold values 122 of FIG. 1. In addition, in a preferred embodiment,the determination of step 212 is made by the processor 114 of FIG. 1.

If it is determined in step 212 that none of the requested amounts ofbraking pressure from step 206 thus far during the braking event havebeen less than the predetermined pressure threshold, then adetermination is made as to whether the braking request is increasing(step 213). In a preferred embodiment, this comprises a determination asto whether the requested amount of braking pressure from a current timeperiod and a current iteration of step 206 is greater than acorresponding amount of braking pressure from an immediately prior timeperiod and an immediately prior iteration of step 206. Also in apreferred embodiment, this determination is made by the processor 114 ofFIG. 1.

If it is determined in step 213 that the braking request is increasing,then an adjusted amount of braking pressure is provided (step 214). In apreferred embodiment, the adjusted amount of braking pressure is equalto a braking pressure applied during an immediately prior time period,so that the braking pressure is applied at a constant rate during thistime. Thus, in a preferred embodiment, the amount of braking pressureapplied is not allowed to increase during this time until the requestedamount of pressure calculated in step 206 is less than the predeterminedpressure threshold. In a preferred embodiment, the braking is applied instep 214 with braking pressure provided to the brake units 106 of FIG. 1based on instructions provided by the processor 114 of FIG. 1.

Conversely, if it is determined in step 213 that the braking request isnot increasing, then braking is applied with braking pressure equal tothe requested amount of braking pressure calculated in step 206 (step215). Specifically, in a preferred embodiment, the braking is applied instep 215 with braking pressure provided to the brake units 106 of FIG. 1based on instructions provided by the processor 114 of FIG. 1,preferably using a corresponding current or most recent value of therequested amount of braking pressure as calculated in a most recentiteration of step 206. As discussed above in connection with step 206,this may or may not reflect a filtered value, depending on whether afilter was applied in step 204. Following step 215, the processpreferably returns to step 202, as additional braking requests arereceived, and the steps of the process 200 continue and repeatthroughout the braking event.

Returning now to step 212, if it is determined in step 212 that one ormore of the requested amounts of braking pressure from step 206 thus farduring the braking event have been less than the predetermined pressurethreshold, then a determination is made as to whether a correspondingcurrent or most recent requested amount of braking pressure from acurrent or most recent iteration of step 206 is greater than thepredetermined pressure threshold (step 216). This determination is alsopreferably made by the processor 114 of FIG. 1.

If a determination is made during step 216 that the correspondingcurrent or most recent requested amount of braking pressure from acurrent or most recent iteration of step 206 is less than or equal tothe predetermined pressure threshold, then the process proceeds to theabove-described step 215. As detailed above, during step 215, braking isapplied with braking pressure equal to the requested amount of brakingpressure calculated in step 206, preferably with braking pressureprovided to the brake units 106 of FIG. 1 based on instructions providedby the processor 114 of FIG. 1, preferably using a corresponding currentor most recent value of the requested amount of braking pressure ascalculated in a most recent iteration of step 206. Also as detailedabove, following step 215, the process preferably returns to step 202,as additional braking requests are received, and the steps of theprocess 200 continue and repeat throughout the braking event.

Conversely, if a determination is made during step 216 that thecorresponding current or most recent requested amount of brakingpressure from a current or most recent iteration of step 206 is greaterthan the predetermined pressure threshold, then braking is appliedinstead with braking pressure equal to the predetermined pressurethreshold (step 218). Specifically, in a preferred embodiment, thebraking is applied in step 218 with braking pressure provided to thebrake units 106 of FIG. 1 based on instructions provided by theprocessor 114 of FIG. 1, with braking pressure in an amount equal to thepredetermined pressure threshold of step 212. Following step 218, theprocess preferably returns to step 202, as additional braking requestsare received, and the steps of the process 200 continue and repeatthroughout the braking event.

Returning now to step 210, if it is determined in step 210 that thevehicle is not stationary, then a determination is made as to whetherthe vehicle has been moving for an amount of time that is less than apredetermined time threshold (step 220). In a preferred embodiment, thepredetermined time threshold is stored in the memory 118 of FIG, 1 asone of the threshold values 122 of FIG. 1. Also in a preferredembodiment, the determination of step 220 is made by the processor 114of FIG. 1. In addition, in a preferred embodiment, this determination isutilized to assess whether or not a transition or rate limiter isneeded. For example, if the vehicle was previously stationary and hasonly recently begun moving, then such a transition or rate limiter isused in a preferred embodiment. In one preferred embodiment, thepredetermined time threshold is 250 milliseconds. However, the value ofthe predetermined time threshold may vary.

If it is determined in step 220 that the vehicle has been moving for anamount of time that is greater than or equal to the predetermined timethreshold, then the process proceeds to the above-described step 215. Asdetailed above, during step 215, braking is applied with brakingpressure equal to the requested amount of braking pressure calculated instep 206, preferably with braking pressure provided to the brake units106 of FIG. 1 based on instructions provided by the processor 114 ofFIG. 1, preferably using a corresponding current or most recent value ofthe requested amount of braking pressure as calculated in a most recentiteration of step 206. Also as detailed above, following step 215, theprocess preferably returns to step 202, as additional braking requestsare received, and the steps of the process 200 continue and repeatthroughout the braking event.

Conversely, if it is determined in step 220 that the vehicle has beenmoving for an amount of time that is less than the predetermined timethreshold, then braking is applied with braking pressure equal to anintermediate or transition value (step 222). The intermediate ortransition value is preferably greater than the predetermined pressurethreshold and less than the corresponding current or most recentrequested amount of braking pressure calculated in step 206.Specifically, in a preferred embodiment, when the vehicle was previouslystationary but has now just begun moving (i.e., for less than thepredetermined time threshold), intermediate or transition values arepreferably used during this time to serve as a smooth transition or ratelimiter to gradually change from providing braking pressure equal to thepredetermined pressure threshold (while the vehicle is stationary) toproviding braking pressure equal to the corresponding current or mostrecent requested amount of braking pressure from step 206 (while thevehicle has been moving for longer than the predetermined amount oftime). In one preferred embodiment, a linear transition may be used.However, this may vary in other embodiments.

Also in a preferred embodiment, the braking pressure in step 222 issimilarly provided with braking pressure provided to the brake units 106of FIG. 1 based on instructions provided by the processor 114 of FIG. 1.In addition, in a preferred embodiment, following step 222, the processpreferably returns to step 202, as additional braking requests arereceived, and the steps of the process 200 continue and repeatthroughout the braking event.

The process 200 thereby provides limiting of braking pressure undercertain appropriate circumstances. Specifically, in accordance with apreferred embodiment, braking pressure is limited to a predeterminedclamp value (referenced above as the predetermined pressure threshold)during step 218 when each of the following conditions are satisfied;namely, (i) the vehicle is stationary, (ii) one or more of the requestedamounts of braking pressure from step 206 thus far during the brakingevent have been less than the predetermined pressure threshold, and(iii) the corresponding current or most recent requested amount ofbraking pressure from the current or more recent iteration of step 206is greater than the predetermined pressure threshold. During thesecircumstances, the reduction or clamping of the braking pressure canserve to reduce excessive braking pressure, braking drag, energyconsumption, pedal feedback, hydraulic fluid consumption, and/or pumpcycling.

Turning now to FIG. 3, a graphical representation 300 is provided ofvarious torque parameters pertaining to the brake controller 104 of FIG.1 and the process 200 of FIG. 2 for an exemplary scenario in which thevehicle is being operated, in accordance with an exemplary embodiment ofthe present invention. Specifically, the graphical representation 300 ofFIG. 1 depicts a wheel speed 302 parameter, an initial driver request304 parameter, a filtered request 306 parameter, and a clamped value 308parameter.

The wheel speed 302 of FIG. 3 represents the one or more wheel speedvalues obtained during step 206 of FIG. 2 by the wheel speed sensors 111and/or the processor 114 of FIG. 1. The initial driver request 304 ofFIG. 3 represents torque values corresponding to the braking requestsobtained or receiving during step 202 of FIG. 2 by the brake pedalsensors 110 and/or the processor 114 of FIG. 1 throughout the brakingevent. The filtered request 306 represents torque values correspondingto the requested amounts of braking pressure calculated during step 206by the processor 114 of FIG. 1 throughout the braking event in anembodiment in which a first order filter was applied during step 204.The clamped value 308 represents a constant torque value correspondingto the predetermined pressure threshold as applied during step 218 ofFIG. 2 based on instructions provided by the processor 114 of FIG. 1.

As shown in FIG. 3, the braking torque is limited to the clamped value308 during the marked time periods 312 and 215. During the marked timeperiods 312 and 215 of FIG. 3, each of the above-described conditions ofFIG. 2 for limiting pressure are satisfied; namely: (i) the vehicle isstationary, (ii) one or more of the requested amounts of brakingpressure from step 206 of FIG. 2 thus far during the braking event havebeen less than the predetermined pressure threshold, and (iii) thecorresponding current or most recent requested amount of brakingpressure from the current or more recent iteration of step 206 of FIG. 2is greater than the predetermined pressure threshold.

In addition, also as shown in FIG. 3, in a preferred embodiment, if therequested amount of braking pressure has not yet dropped below thepredetermined threshold and the requested amount of braking pressure isincreasing, the braking pressure is held at a constant level during suchtime periods. This is depicted in regions 316, 318, and 320 in FIG. 3 inaccordance with an exemplary embodiment.

Accordingly, improved methods and systems are provided for controllingbraking of a vehicle. The improved methods and systems provide forlimits on braking pressure in appropriate circumstances when the vehicleis stationary and one or more other conditions are satisfied, to therebypotentially reduce excessive braking pressure, braking drag, energyconsumption, pedal feedback, hydraulic fluid consumption, and/or pumpcycling.

It will be appreciated that the disclosed methods and systems may varyfrom those depicted in the Figures and described herein. For example, asmentioned above, the brake controller 104 of FIG. 1 may be disposed inwhole or in part in any one or more of a number of different vehicleunits, devices, and/or systems. In addition, it will be appreciated thatcertain steps of the process 200 may vary from those depicted in FIG. 2and/or described herein in connection therewith. It will similarly beappreciated that certain steps of the process 200 may occursimultaneously or in a different order than that depicted in FIG. 2and/or described herein in connection therewith. It will similarly beappreciated that the disclosed methods and systems may be implementedand/or utilized in connection with any number of different types ofautomobiles, sedans, sport utility vehicles, trucks, and/or any of anumber of other different types of vehicles, and in controlling any oneor more of a number of different types of vehicle infotainment systems.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or exemplary embodiments are only examples, and arenot intended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the foregoing detailed description willprovide those skilled in the art with a convenient road map forimplementing the exemplary embodiment or exemplary embodiments. Itshould be understood that various changes can be made in the functionand arrangement of elements without departing from the scope of theinvention as set forth in the appended claims and the legal equivalentsthereof.

We claim:
 1. A method for controlling braking of a vehicle during abraking event, the method comprising the steps of: calculating, via aprocessor, a plurality of pressures during the braking event, each ofthe plurality of pressures calculated based on a different one of aplurality of driver requests detected via a sensor; and providing, viathe processor, pressure equal to a corresponding one of the plurality ofpressure values if the vehicle is stationary and any of the plurality ofpressures are less than a predetermined pressure threshold; andproviding, via the processor, pressure equal to the predeterminedpressure threshold if the vehicle is stationary and none of theplurality of pressures are less than the predetermined pressurethreshold.
 2. The method of claim 1, wherein the vehicle has a wheel,and the method further comprises the steps of: obtaining a wheel speedvalue from a wheel speed sensor; and determining, via the processor,whether the vehicle is stationary based upon the wheel speed value. 3.The method of claim 1, further comprising the steps of: providing, viathe processor, pressure equal to an intermediate pressure value that isgreater than the predetermined pressure threshold and less than thecorresponding one of the pressure values., if each of the followingconditions (a)-(b) are satisfied, namely: (a) the vehicle is moving, and(b) the vehicle has been moving for less than a predetermined amount oftime.
 4. The method of claim 1, further comprising the step of:providing, via the processor, a constant pressure during a timeinterval, if conditions (a) and (b) are both satisfied: (a) theplurality of pressures have each been greater than the predeterminedpressure threshold; and (b) the plurality of pressures are increasingduring the time interval.
 5. A system for controlling braking of avehicle during a braking event, the system comprising: a sensorconfigured to detect a plurality of driver requests during the brakingevent; and a processor coupled to the sensor and configured to at leastfacilitate: calculating a plurality of pressures during the brakingevent, each of the plurality of pressures calculated based on adifferent one of the plurality of driver requests; and providingpressure equal to a corresponding one of the plurality of pressurevalues if the vehicle is stationary and any of the plurality ofpressures are less than a predetermined pressure threshold; andproviding pressure equal to the predetermined pressure threshold if thevehicle is stationary and none of the plurality of pressures are lessthan the predetermined pressure threshold.
 6. The system of claim 5,wherein the vehicle has a wheel, and the system further comprises: asecond sensor configured to obtain a wheel speed value, wherein theprocessor is further configured to determine whether the vehicle isstationary based upon the wheel speed value.
 7. The system of claim 5,wherein the processor is further configured to at least facilitate:providing a constant pressure during a time interval, if conditions (a)and (b) are both satisfied: (a) the plurality of pressures have eachbeen greater than the predetermined pressure threshold; and (b) theplurality of pressures are increasing during the time interval.
 8. Thesystem of claim 5, wherein the processor is further configured to atleast facilitate providing pressure equal to an intermediate pressurevalue that is greater than the predetermined pressure threshold and lessthan the corresponding one of the pressure values., if each of thefollowing conditions (a)-(b) are satisfied, namely: (a) the vehicle ismoving, and (b) the vehicle has been moving for less than apredetermined amount of time.
 9. The system of claim 8, wherein theprocessor is further configured to at least facilitate providingpressure equal to the corresponding one of the plurality of pressures ifthe vehicle has been moving for more than the predetermined amount oftime.